JP2009-244134A discloses a non-contact type torque sensor that detects steering torque acting on a steering shaft using magnetic force. The torque sensor includes an input shaft and an output shaft supported in a housing to be free to rotate, a torsion bar that transmits the steering torque between the input shaft and the output shaft, a magnetism generating portion fixed to the input shaft, a rotary magnetic circuit portion fixed to the output shaft, a fixed magnetic circuit portion fixed to the housing, and a magnetism sensor that detects a magnetic flux density conducted to the fixed magnetic circuit portion.
When the steering torque acts on the torsion bar such that the torsion bar undergoes torsional deformation, relative rotation direction positions of the magnetism generating portion and the rotary magnetic circuit portion vary. Accordingly, the magnetic flux density conducted to the fixed magnetic circuit portion from the magnetism generating portion via the rotary magnetic circuit portion varies. The magnetism sensor outputs a signal corresponding to the magnetic flux density. The torque acting on the torsion bar is detected on the basis of the signal output from the magnetism sensor.